For much of the Cold War 21 SAS's role was to provide stay-behind parties in the event of a Warsaw Pact invasion of western Europe (as part of the Corps Patrol Unit alongside 23 SAS and The Honourable Artillery Company).
I didn't add any video links in the previous SAS post - but I had seen some on Youtube. So these relate to the SAS in the Falkland's War so are not totally relevant - but the uniform's etc are all the same.
So without further ado...
Here are some links to some Weaponology episdoes on the SAS - a bit OTT but it has some interesting stuff anyway:
These ones are from the excellent SAS Heroes Show - recently shown on BBC Knowledge in Oz - this one is on the Iranian Embassy Raid in 1980:
That's probably enough for now...